1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and an image processing program which are suitable for use in displaying an image represented by image data having a significantly large number of pixels on a display device having a standard number of pixels.
2. Description of the Related Art
In recent years, as digital transmission technology and video data compression and encoding technology have advanced, the resolution of television images has increased. For example, a resolution of 1920 pixels×1080 lines in interlace scanning (1080I) has been realized for so-called high-definition video in current terrestrial digital broadcasting. In progressive scanning, a resolution of 1920 pixels×1080 lines (1080P) has been realized as a standard. Further, many monitor devices that are used for displaying such television images and have effective display pixels whose number corresponds to the resolution of high-definition video have been developed. An interface standard for transmitting television signals based on high-definition video has been defined as the High-Definition Multimedia Interface (HDMI).
In contrast, the technique of obtaining an image covering a wide range that is significantly wider than the angle of view of an image capturing apparatus (hereinafter called a “panoramic image”) by sequentially capturing images while continuously moving an image capturing range so that the captured images become continuous and connecting the captured images in a predetermined manner has been developed. Japanese Unexamined Patent Application Publication No. 2007-43505 describes a method of controlling a camera at the time of capturing a panoramic image and a method of generating a panoramic image from image data captured under such control.
A panoramic image having a significantly greater number of pixels than that of image data obtained in one shot using a general image capturing method. In other words, when a panoramic image is regarded as image data representing one image, the panoramic image has a significantly higher resolution than that of image data obtained in one shot taken by using a general image capturing method.
For example, in recent years, image pickup devices such as charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) imagers have become more sophisticated. Even with the use of generally used digital still cameras that are designed to be compact and light-weight (so-called “compact cameras”), an image with a resolution of, for example, 4000 pixels×3000 pixels or 3264 pixels×2448 pixels, which is higher than that of high-definition video, can be easily captured. Digital single-lens reflex cameras can capture image data with a yet higher resolution. A panoramic image is generated by connecting items of such image data, each having a number of pixels of, for example, 4000 pixels×3000 pixels or 3264 pixels×2448 pixels. Therefore, the total number of pixels of the panoramic image is significantly greater than the number of pixels of the above-described high-definition video, for example, and is a vast number of pixels.